Validating an instrument for measuring leadership responsibilities of Hong Kong vice-principals: A Rasch analysis

Literature has substantiated a growing trend in the recognition of the important role vice-principals play in schools which is evident in the increasing amount of work focusing on their roles and responsibilities, job satisfaction, and career aspiration. Amongst the empirical studies, factor analysis is the most frequently used statistical tools. A possible drawback of using factor analysis is the lack of a common framework based on which comparison and consolidation of research findings produced by various researchers can be made as different researchers literally adopt different sets of responsibility roles derived in their studies. A more serious deficiency of using factor analysis is the lack of an objective measure in the analysis. The study aims to validate an instrument to measure Hong Kong secondary school vice-principals’ responsibilities using Rasch Analysis. Based on responses from 331 vice-principals, Rasch analysis was applied to assess the model-data fit of the 56 4-point Likert items , which included checking for optimal response categories usage, person ability-item difficulty targeting, person and item reliabilities, principal component analysis of standardised residuals and test of differential item functioning (DIF). The overall results showed that except for a few misfitting items all other items can meaningfully contribute to measuring a single construct at good reliability. In particular, among the items on the area of “instructional leadership”, where there is lack of consensus among schools as the literature suggested, DIF analysis was also performed to evaluate the differential performance among respondents from different school subsidy types and school bandings.